Javascript Program For Recursive Selection Sort For Singly Linked List – Swapping Node Links

// Javascript implementation of recursive 
// selection sort for singly linked list 
// | Swapping node links     

// A Linked list node
class Node 
{
    constructor(val) 
    {
        this.data = val;
        this.next = null;
    }
}

// Function to swap nodes 'currX' and 
// 'currY' in a linked list without 
// swapping data
function swapNodes(head_ref, currX,  
                   currY,  prevY) 
{
    // Make 'currY' as new head
    head_ref = currY;

    // Adjust links
    prevY.next = currX;

    // Swap next pointers
    let temp = currY.next;
    currY.next = currX.next;
    currX.next = temp;
    return head_ref;
}

// Function to sort the linked list using
// recursive selection sort technique
function recurSelectionSort(head) 
{
    // If there is only a single node
    if (head.next == null)
        return head;

     // 'min' - pointer to store the node 
     // having minimum data value
     let min = head;

     // 'beforeMin' - pointer to store node 
     // previous to 'min' node
     let beforeMin = null;
     let ptr;

     // Traverse the list till the last node
     for (ptr = head; ptr.next != null; 
          ptr = ptr.next) 
     {
         // if true, then update 'min' and 
         // 'beforeMin'
         if (ptr.next.data < min.data) 
         {
             min = ptr.next;
             beforeMin = ptr;
         }
     }

     // if 'min' and 'head' are not same,
     // swap the head node with the 'min' node
     if (min != head)
         head = swapNodes(head, head, 
                          min, beforeMin);

     // recursively sort the remaining list
     head.next = recurSelectionSort(head.next);

     return head;
}

// Function to sort the given linked list
function sort(head_ref) 
{
    // If list is empty
    if ((head_ref) == null)
        return null;

    // Sort the list using recursive 
    // selection sort technique
    head_ref = recurSelectionSort(head_ref);
    return head_ref;
}

// Function to insert a node at the
// beginning of the linked list
function push(head_ref, new_data) 
{
    // Allocate node
    let new_node = new Node();

    // Put in the data
    new_node.data = new_data;

    // Link the old list to the 
    // new node
    new_node.next = (head_ref);

    // Move the head to point to the 
    // new node
    (head_ref) = new_node;
    return head_ref;
}

// Function to print the linked list
function printList(head) 
{
    while (head != null) 
    {
        console.log(head.data + " ");
        head = head.next;
    }
}

// Driver code
let head = null;

// Create linked list 10.12.8.4.6
head = push(head, 6);
head = push(head, 4);
head = push(head, 8);
head = push(head, 12);
head = push(head, 10);

console.log("Linked list before sorting:");
printList(head);

// Sort the linked list
head = sort(head);

console.log("Linked list after sorting:");
printList(head);
// This code is contributed by todaysgaurav